Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

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Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Matador » Mar 19 2017 9:52pm

Last year, I got myself a BBSHD 1000W kit. In the process of building a 14S battery, I search for a good BMS. I finally ordered 2 BMS (minimum order quantity) from BestTech Power in China, as people said they were good quality. But with shipping, costums, local taxes and exchange rate, it ended up costing me 240 canadian dollars for the two pieces. Yikes !!! In the process of wiring the BMS top a 14S9P I assembled in august 2016, I did something wrong. I think I connected a certain balance lead in a wrong place, and in less than a second, I smelled the magic blue smoke (as they say) :wink: . Anyway, I did the second BMS wiring good and it worked, but that 120 dollars gone in smoke left me a bitter taste even though it was clearly my fault (lesson learned).

The BMS model is a good one to : HCX-D131 from BesTech Power :
14S Li-Ion
Rated 80A continuous, 200A peak discharge
20A charge
Balance current is on the High Side for a BMS (168 mA per string).
Balance @ 4.20V
LVC : 3.00V ; HVC : 4.28 V

Here’s the datasheet of the HCX-D131 80A 14S Li-Ion :
分口 14S D131 Li-ion BesTech Power datasheet.pdf
(154.98 KiB) Downloaded 108 times
So I thought why not examine the thing, try to identify components, and REPAIR IT…. No, I’m not looking for a bottle of magic blue smoke ;), but a little help from you kind folks of the endless sphere would be very appreciated. At the same time, this post is also a contribution to the whole community, I did put in my best effort to take pictures or photomicrographs of every component I could find. I just don’t know what the codes mean…. So I’m kind of stuck…

Anyways, If you recognise a component of this BMS from the picture, please post the answer here. Even better if you find de datasheet of the component and post the link. Or if you just have some general comments. I figured, many people here buy BMSs from BesTech Power, so documenting the components might help other people fix their electronics if they have similar issures.

This, is an autopsy examination of the BesTech Power 14S Li-Ion, 80A HCX-D131 BMS. I will start with general gross pictures, then go ahead with microscopic examination ( I took my old microscope, and my IPod touch to take pictures, photoshoped everything, and made drawings).

Goals here : 1 - Sharing knowledge. 2 – Find a way to repair this BMS (I identified 3 fried components under the scope, one of which I have no clue what it does), 3 – Share discussion so we can all contribute to identify every components here (I NUMBERED THEM FOR EASE OF RECALLING).

GROSS EXAMINATION :
The good, the bad, and the ugly :
IMG_0798.JPG
My dead HCX-D131 :
Dead HCX-D131.jpg
Nothing seems wrong visually yet...
After splitting in halves (the clamshell approach) we can see :

The outer surfaces : still looks okay
Clamshell outside.jpg
Revealing the MosFETs :mrgreen:
Mosfeat revealed.jpg
Mosfets x 20.jpg
All looking good. Closeup :
Mosfets close-up.jpg
Clamshell approach, Inside side :
Clamshell inside.jpg
Close inspection :
Burnin 1.jpg
Burnin 2.jpg
Burnin 3.jpg
:idea: TIME FOR SOME X-RAYS NOW :
IMG_0820.JPG
IMG_0818.JPG
IMG_0801.JPG
IMG_0802.JPG
IMG_0810.JPG
IMG_0814.JPG
IMG_0816.JPG
Well then, time to pull out the scope, get ready for some serious MICROMAPPING :
IMG_0795.JPG
Please see next one of my post down here.

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Matador » Mar 19 2017 10:27pm

MICROSCOPY :
Let's start the microscopic examination with the study of the components of the typical BALANCING ROWS of this BMS model. If you recognise any of these components (hieroglyophs for me), please post it :
Localisation balancing row.jpg
Balancing Row_.jpg
There is also some electronic component on the side of the PCB board:
Localisation side components.jpg
Side components.jpg
All looks in good shape.

But there are some burnt components (that smoke you know) :
Burnt components.jpg
Please help me identify each of these components. Maybe I can repair this... Maybe people can build there own BMS based on or just copying this BMS layout.
With your help, I plan to make a summary table of each of these components and post it here... If we can find them.

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Matador » Mar 19 2017 10:41pm

I already figured all the resistor components though. No need to post on these :

Component 1 "101" : 100 Ohm 1W resistor (Packet form : 2512 ; size : 6.35 x 3.2 mm)
Component 6 "102" : 1 kOhm 1/16 W resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm)
Component 8 "471" : 470 Ohm 1/16 W resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm)
Component 11 "225" : 2.2 MOhm 1/16 resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm)
Component 16 "104" : 100 kOhm 1/16 W resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm)
Component 17 "202" : 2 kOhm 1/16 W resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm)
Component 18 "685" : 6.8 MOhm 1/16 W resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm)
Component 20 "103" : 10 kOhm 1/16 W resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm).

I really don't know what de multilayered ceramic capacitor values are.... They seem to be of 0603 packet (size : 1.6 x 0.8 mm). No numbers on these... Can I find out ?

And all the other components except the big mosfets are just complete chinese for me.... I'm completely clueless.

Here's a synoptic mapping I make (diagram) of the complete BMS unit components :
Mapping HCX-D131 80Amp 14S Li-Ion.jpg
Any help appreciated, for the benefit of everyone :mrgreen:
Matador
Last edited by Matador on Mar 20 2017 6:50am, edited 1 time in total.

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Manny » Mar 20 2017 2:49am

the chips you labels as GCLQ and G3LN are single battery protection ic like S-8241

datasheet:
http://www.mouser.com/ds/2/360/S8241_E-5644.pdf

the two chips have different thresholds when the voltage rises the one closest to the 100 ohm resistors will activate the balans resistor through the AFGV (mosfet).
if the voltage keeps rising the second chip will activate the main mosfet bank and disconnect the battery from the charger.

the L2H probably a pnp transistor used to "communicate" the signals form the chips to the main mosfets.

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Punx0r » Mar 20 2017 5:21am

Best guess: you miss-wired a balance lead, so you had much more than 4V on one channel, the board detected this as an over-voltage cell and tried to balance it, but because the excess voltage was much greater than normal so was the balancing current and you burned up either the dump resistors and/or whatever switches them. Should be fixable?

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Matador » Mar 20 2017 7:39am

Manny wrote:the chips you labels as GCLQ and G3LN are single battery protection ic like S-8241
datasheet: http://www.mouser.com/ds/2/360/S8241_E-5644.pdf
The two chips have different thresholds when the voltage rises the one closest to the 100 ohm resistors will activate the balans resistor through the AFGV (mosfet).
if the voltage keeps rising the second chip will activate the main mosfet bank and disconnect the battery from the charger. the L2H probably a pnp transistor used to "communicate" the signals form the chips to the main mosfets.
Thanks Manny. That's an absolutely awesome find. The explaination help me understand the circuit more. Love to reverse engeneer the thing... I could probably even modify to lower balancing voltage to 4.10V instead of 4.20V in the future, by changing some components....
Punx0r wrote:Best guess: you miss-wired a balance lead, so you had much more than 4V on one channel, the board detected this as an over-voltage cell and tried to balance it, but because the excess voltage was much greater than normal so was the balancing current and you burned up either the dump resistors and/or whatever switches them. Should be fixable?
Yes, I remember that, I wasn't sure which lead it was that shorted though, but judging from the B8 pin that's a bit cooked (seen under microscope), I guess that's the guilty one. If it's B8 that shorted with B1, Yikes ! No wonder 32 volts blew a few components.
Cooked B8 pin.jpg
Fixable ? I certainly hope to buy some new chips, practice my microsoldering technique and replace the part to put the BMS back to usage (once I restest it's functionning of course).... Hopefully, different brand have the same exact specification for the same exact component number. (I also noticed that BesTech Power also sell just the lower board itself as a "Cell Balance Board" ( http://bestechpower.com/balanceboard/JH-D131A.html ), but I don't want to double my price with shipping/taxes/customs/exchange rate this time...
Last edited by Matador on Mar 20 2017 12:59pm, edited 2 times in total.

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Matador » Mar 20 2017 9:37am

Component parts.jpg
IDENTIFIED SO FAR ( Legend : BLACK - Fully identified genuine OEM part ; Blue - Identification of closest similar part ; RED - Unidentified):

Component 01 "101" : 100 Ω 1W resistor (Packet form : 2512 ; size : 6.35 x 3.2 mm)
Component 02 "AFGV 19" : I measured 2.9 x 1.5 mm (SOT-23?)
Component 03 "AFKV 17" : I measured 2.9 x 1.5 mm (SOT-23?)
Component 04 "GCLQ" : Might come from here http://blog.sina.com.cn/s/blog_a377c9720101fhnc.html Google translate : https://translate.google.ca/translate?h ... 1fhnc.html
Component 05 "GCLP" : Might come from here http://blog.sina.com.cn/s/blog_a377c9720101fhnc.html Google translate : https://translate.google.ca/translate?h ... 1fhnc.html
Component 06 "102" : 1 kΩ 1/16 W resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm)
Component 07 [No marking] :
Component 08 "471" : 470 Ω 1/16 W resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm)
Component 09 "G3JN" : CLOSEST : S-8261 ABJMT-G3JT2x http://datasheet.sii-ic.com/en/battery_ ... 8261_E.pdf (thanks to Manny)
Component 10 "G3JQ" : CLOSEST : S-8261 ABJMT-G3JT2x http://datasheet.sii-ic.com/en/battery_ ... 8261_E.pdf (thanks to Manny)
Component 11 "225" : 2.2 MΩ 1/16 resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm)
Component 12 "2L I" :
Component 13 "2L F" :
Component 14 "A" :
Component 15 "G1 J" :
Component 16 "104" : 100 kΩ 1/16 W resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm)
Component 17 "202" : 2 kΩ 1/16 W resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm)
Component 18 "685" : 6.8 MΩ 1/16 W resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm)
Component 19 "TB02-BB8D 90°C BAOZHU" : TB02-BB8D-90 Thermal Protection Switch (Normally closed ; 2 Amp ; in plastic housing). Datasheet : https://www.limitor.com/limitorproject/ ... glisch.pdf
Component 20 "103" : 10 kΩ 1/16 W resistor (Packet form : 0603 ; size : 1.6 x 0.8 mm).
Component 21 "FB3307Z [Brand Logo] P618D [date code] 4YAO [assembly lot code] " : IRFB3307Z PbF HEXFET Power Mostfet (Packet form : TO-220AB). Datasheet : http://www.infineon.com/dgdl/irfs3307zp ... 3691d7216c
BMS HCX D131-C (80Amps) Components (legend).png
Balancing Row_.jpg
Side components.jpg
Last edited by Matador on Mar 29 2017 8:30am, edited 2 times in total.

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by fechter » Mar 20 2017 10:15am

Components 2 and 3 are transistors. You could possibly use a diode check meter on a good one to determine if NPN, PNP or MOSFET.

Components 4 and 5 are voltage detector chips. The markings are the part number suffix as Manny pointed out. It definitely looks like a Seiko chip. I did find a reference to a part with that suffix: S-8261ABJMD-G3JT2G G3JN
Datasheet: http://www.mouser.com/ds/2/360/S8261_E-89.pdf
Mouser page: http://www.mouser.com/ProductDetail/SII ... PFZQ%3D%3D

Component 14 is a diode
Component 19 is a thermostatic switch, 90C
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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Matador » Mar 20 2017 10:33am

This Quality Control Sheets help a bit in trying to find the components :
D131LI14S80A-02(2016-7-5).pdf
(104.98 KiB) Downloaded 48 times
They say : IC of control = G3J ; MOS : 3307 ; Balance IC : GCL. 10 MOS for charging, 10 MOS for discharging.

I think they made a mistake on the QC sheet though, stating a "4.3V" as a the "Balance voltage for single cell", in the first column. Conflicting the 4.2V Balance voltage value in the second line of the table . That would just not work as the "Overcharge Protection Voltage" is set way below that, at 4.28 ± 0.025 V.

In addition to that, the pre-manufacturing datasheet states an "Balance voltage" set at 4.20 ± 0.025 V
分口 14S D131 Li-ion BesTech Power datasheet.pdf
(154.98 KiB) Downloaded 31 times
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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Matador » Mar 20 2017 10:45am

fechter wrote:Components 2 and 3 are transistors. You could possibly use a diode check meter on a good one to determine if NPN, PNP or MOSFET.

Components 4 and 5 are voltage detector chips. The markings are the part number suffix as Manny pointed out. It definitely looks like a Seiko chip. I did find a reference to a part with that suffix: S-8261ABJMD-G3JT2G G3JN
Datasheet: http://www.mouser.com/ds/2/360/S8261_E-89.pdf
Mouser page: http://www.mouser.com/ProductDetail/SII ... PFZQ%3D%3D

Component 14 is a diode
Component 19 is a thermostatic switch, 90C
Awesome ! Thanks Fechter.

I'm still unsure.... Is there a difference in function between the component 9 (G3JN) and component 10 (G3JQ) or are they exactly the same thing ? Is the last letter just a date/batch code or something ?
Last edited by Matador on Mar 20 2017 4:20pm, edited 1 time in total.

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by fechter » Mar 20 2017 2:19pm

If you contacted Seiko, they might be able to tell you exactly. Unfortunately, I don't see those exact suffixes in the datasheet. The last letter seems to be halogenated or not (we don't care). Those chips could be custom values not listed in the datasheet also. Somebody at Seiko can probably make sense of it but they usually won't talk to you unless they think you want to buy 5,000 pieces. It is OK to "exaggerate" when contacting them.

In a typical BMS, the shunts will be triggered at one voltage (4.2v for example) and the over voltage protection triggers at a slightly higher voltage, like 4.3v.

If you have a working channel, a precision variable power supply and some really skinny needle probes, you might be able to measure the exact voltages where it triggers. Since the set points have hysteresis, direct measurement is challenging.

Henry at BesTech might be able to tell you also. He should at least know what the voltage set points are.
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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Matador » Mar 20 2017 4:44pm

fechter wrote: If you have a working channel, a precision variable power supply and some really skinny needle probes, you might be able to measure the exact voltages where it triggers. Since the set points have hysteresis, direct measurement is challenging. Henry at BesTech might be able to tell you also. He should at least know what the voltage set points are.
I wish ! All I have is an old Tectronix 2215 60 Mhz Analog Oscilloscope with it's original Probe, a crappy Mastercraft multimeter, 3 CellLog 8M devices (on a same fully charged 18650 cell, I read 4.199V, 4.198V and 4.204 V), and a crappy 45W Adjustable linear power supply I made with a scavenged transformer from a trashed stereo, a 10A bridge rectifyer, a 4700 uF capacitor, a LM350K, 2 resistor trim pots (corse and fine) for adjusting voltage (I cannot regulate current), a homemade shunt resistor from wire coil and 2 analog meter displays ... Oh, also have a BC168, a SkyRC ImaxB6 mini, 3 Foxnovo 4S Digital Chargers, and three soldering irons...
IMG_1057.JPG
IMG_1054.JPG
IMG_1060.JPG
chargers.jpg
chargers.jpg (104.98 KiB) Viewed 1640 times
I guess I'm just an amateur :oops: I need some more serious equipment... If I had the cash, I'd buy a HIOKI 3550 battery tester and an Agilent LTC2400 digital voltmeter!

But damn I really want to solve this circuit...
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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Matador » Mar 20 2017 10:45pm

In restospective, I think my CellLogs 8M are actually pretty good for measuring voltages... Could use them.
For the ceramic multilayered capacitors, since they have no markings on them, is there a way to measure their capacity ??? (so small, they must be in the nF or pF range I guess).

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by fechter » Mar 21 2017 8:11am

I find it's fairly challenging to measure those set points even with good test equipment. Each cell circuit is independent so you can pick one and apply a simulated cell voltage. To measure the shunt voltage, you can put a meter across the shunt resistor to tell when it turns on and slowly increase the input voltage until you see it turn on. There is some hysteresis in the voltage, so once it turns on, it will stay on until the input drops by 20mV or so, then it will turn off.
Measuring the OVP is similar but you need to find the output pin of the voltage detector and see when that toggles.
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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by jonescg » Mar 28 2017 7:47am

This is why I love the ES forum :D

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Matador » Mar 29 2017 8:02am

SPOTTED !
Component 19 : TB02-BB8D 90°C Thermal protector (Normally closed)
TB02-BB8D-90.jpg
TB02-BB8D-90.jpg (205.95 KiB) Viewed 2655 times
TB02-BB8D-90 by chinese company BAOZHU (company sheet : https://img.ozdisan.com/ETicaret_Dosya/ ... 008916.pdf)
Datasheet (for the Baozhu component): https://www.limitor.com/limitorproject/ ... glisch.pdf
Non-OEM seller : http://www.conrad.com/ce/en/product/507 ... ure-sensor

Previously posted COMPONENT PART LIST UPDATED.

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by methods » May 02 2017 12:33pm

Awesome Thread!

Subscribed.

-methods
Increasing battery voltage and controller current limit will result in a non linear experience

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by methods » May 02 2017 12:41pm

Matador wrote:
....Yikes !!! In the process of wiring the BMS top a 14S9P I assembled in august 2016, I did something wrong. I think I connected a certain balance lead in a wrong place, and in less than a second, I smelled the magic blue smoke (as they say) ....


...No, I’m not looking for a bottle of magic blue smoke ;), ....

You know brother... someone suggested that I modify my new website to include a PayPal section. We may just start selling magic smoke again.

I have found that the pour-bottle did not work that well. We only had success with the squeeze bottle, where you can get the replacement smoke very close to the crackly-burned component. We have had great success stories.

- seriously tho -

That failure should be very easy to find.
I need to go back and read your thread... but one way I do it (when not visible... and it almost always is)... is to:

* Discharge everything as much as possible. Both good and bad boards.
* Start with black lead tied to ground.
* Start probing pins, closest to your mistake, on both boards.
* Most readings will be the same... some will be different
* When you find readings that are SIGNIFICANTLY different you can hone in on the failure. Maybe a mostfet shorted or diode blew open...
* Basically you are just playing around with leakage currents. Sometimes you need to take a voltage measurement, charge up the caps around it, then read the bleed into Ohms measurement.

Find lots of stuff that way...
But even more with a good microscope. Micro-cracks. If you actually smelled smoke and saw smoke then the failure (or failures) will be obvious.

Now... to read your thread.... as I should have BEFORE replying
(my forum edict has grown a tarnish)

-methods
Increasing battery voltage and controller current limit will result in a non linear experience

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by methods » May 02 2017 1:03pm

It seems Fechter dropped the name of the support personality... I would contact him in the following way:

* Explain exactly what you did in the fewest words possible.
* Express clearly that you have no intention of getting a refund or return
* He has probably seen units come back on return 100 times where someone did something similar. No doubt he just scrapes the bad parts off the board, does a repair, cleans well, tests, and sells as new.

If he is an enthusiast... he may send you (for a small fee) a "replacement parts bag" for doing the repair. What you are doing here is free advertising. I am ALREADY thinking about buying one... so your advertising theme is working well for the supplier.

All paths lead back to ground. Probe around for the path that your high voltage took. Hopefully it found ground before it found any multi-pin IC's

Start at the channel... measure the 3 pin parts... They have either a Base, Collector, Emitter.... or a Gate, Drain, Source.

BJT will measure as diodes between the Collector Base, Emitter Base. Measure these both ways in diode mode.
Of course you need to determine which legs are which... Experimental approach.

The voltage detector parts are limited to 6V. When they smoke they often blow a hole in them. Dont worry to much about the exact part number... they are all the same except for the precise trim voltage. If they had a resistor inline it is probable that they survived.

Look for diodes... diodes (while working...) shunt off transient voltages.
When hit with a constant over-voltage they clamp hard and blow.
Two pin parts - usually black. Rated for higher voltage but not continuous current... they can fail and be invisible. Super easy to test. The circuit will often work without them - but best to replace them.

You may consider powering up the circuit... but through some 1K or 1K resistors at each tap. This will allow you to assess as described above (by probing around) but in a current limited way. For instance... if you wire up all your balance taps.. but through current limiting resistors... all good channels should display your 3.XV... while one channel may show something very different. That would indicate a low resistance path to ground. Or... it may indicate no voltage... which may be an open.

You have good tools. You will succeed if you keep at it.

....

To save Money Caps (especially ceramic) are often of lower voltage rating - like 15V
~30V will blow them off the board

Transistors are usually rated for high enough voltage
Mosfets... probably high enough
Sensor Chips - clamped at 6V and will blow
Resistors are easy to test, do not often fail, and are visible (usually) when they have failed.
Diodes are rated for higher voltage but burn upon continuous current. Look for micro-cracks
Traces can easily blow out before components. The cracks can be tiny... the procedure I describe where you "probe around" and expose what the eye can not see as a relative (as opposed to absolute) measurement.

We trust Fluke for these sorts of fiddle-measurements. Other brands work... but Cheap DMM's will just waste your time. They can be had with a blow fuse on Ebay for $50

For voltage... we use Sorsen DCS Series Supplies. CC/CV. Programmable. Couple thousand new, couple hundred used on Ebay. Usually with a bad fan which is $30 to fix.
They allow you to set a very low current limit and then stimulate with the desired voltage to assess inputs. Super useful... MUST have a current limited supply on hand.

-methods
Increasing battery voltage and controller current limit will result in a non linear experience

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by vex_zg » Aug 20 2017 2:32pm

matador, did you find manage to find anywhere the GCLQ part? I also have a fried BMS / one balancing circuit and would like to fix it, I onlz need one GCLQ element.

This was my mini investigation
https://endless-sphere.com/forums/viewt ... d#p1312647

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Matador » Aug 20 2017 3:23pm

vex_zg wrote:matador, did you find manage to find anywhere the GCLQ part? I also have a fried BMS / one balancing circuit and would like to fix it, I onlz need one GCLQ element.

This was my mini investigation
https://endless-sphere.com/forums/viewt ... d#p1312647
Nice to some more people trying to make the most out of this nifty BMS.
Hadn't had much luck finding it because I'm pretty sure is made from a generic chinese company.
Thus documentation (aka datasheet) are really hard to find.

Henry at BesTech might be able to hook you up with some of his parts... THat would be the easiest way. I remember fetcher mentionned him previously in this thread.

Closest I got to finding that GCLQ part is here : http://blog.sina.com.cn/s/blog_a377c9720101fhnc.html
Translate google : https://translate.google.ca/translate?h ... 1fhnc.html

I must say, I left all my ebike stuff In canada (i'm in NYC for the next 1.8 years or so)... Bought a slow (20 mph) ebike locally for 600USD (with 1 year old 36V 22 AH battery) to go by manhattan : https://endless-sphere.com/forums/viewt ... =4&t=89258
When I come back to Canada, I'll have to play with it some more.


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vex_zg   100 W

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by vex_zg » Aug 21 2017 5:56am

ah yes I've seen the thread with the arrow bikes. NYC is quite a busy place to live. Quite the opposite of Stockholm outskirt I am in now.

I was thinking to add an array of leds connected to the Balance resistors so one could see when balancing is taking place (on it's own).

I sent an email to besttech asking for those parts, but I don't have Harry's direct contact. If somebody has it please write it here or PM.

It would really inspire confidence if they would provide repair parts, let' see what happens.

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Matador   10 kW

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by Matador » Aug 22 2017 10:56pm

I'd be very curious nad interested to by spare parts too. The led mod would also be hot !

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fechter   100 GW

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by fechter » Aug 22 2017 11:35pm

I've seen some of their boards that have the spots for the LEDs and resistors, just not populated. The old Signalab (Ping) boards had those and I really thought it was a worthwhile feature. On most, the SMD bleeder resistors are big enough you could just stick the LEDs on top of them if there aren't vacant spots for them.

Another crazy idea I had was to paint the bleeder resistors with thermochromic paint that changes color when it gets warm. We just want to know whether the thing is on or off.
"One test is worth a thousand opinions"

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izeman   10 GW

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Re: Autopsy of a dead BestTech Power HCX-D131 14S 80A BMS

Post by izeman » Aug 23 2017 4:51am

has anyone of you an idea where to add an ON/OFF switch to use the BMS as switch between battery and controller?
i put a switch between the thermal control switch which works, but you need to reset the bms afterwards to make it work again, so this method is not appropriate. any other ideas? i'd like to get rid of the extra inrush limiter i installed, it's just an additional component adding complexity to the system.

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